1. Field of the Invention
The present invention relates to the field of semiconductor processing. More particularly, the present invention relates to an apparatus and method for transporting substrates through a semiconductor processing system, wherein the apparatus and method include a temperature control mechanism. Further, the present invention relates to an apparatus and method for transporting substrates through a semiconductor processing system to generate a poly silicon film.
2. Background of the Related Art
In the semiconductor industry, there are generally two primary methods of transporting substrates through a processing system. One traditional method uses a xe2x80x9ccluster toolxe2x80x9d configuration, as shown in FIG. 1. A cluster tool platform generally refers to a modular, multi-chamber, integrated processing system. This type of processing system typically includes central wafer handling vacuum chambers 20, 32, and a number of peripheral processing chambers 24, 26, 28, and 36, which are generally arranged in a cluster around the central chambers. Multiple substrates or wafers 22 for processing are generally stored in cassettes 10, and are loaded/unloaded from load locks 12, 14 and processed under vacuum in various processing chambers without being exposed to ambient conditions. The transfer of wafers 22 for the processes is generally managed by a centralized robot 16 in a wafer handling vacuum chamber 20 or robot 30 in a second wafer handling vacuum chamber 32, both of which are generally maintained under vacuum conditions. A microprocessor controller 38 and associated software is provided to control processing and movement of wafers. In operation, a cluster tool configuration will generally receive a substrate from a cassette 10 and process the substrate through a predetermined sequence of central wafer handling chambers 20, 32 and peripheral processing chambers 24, 26, 28, and 36 in order to generate the desired material and pattern on a wafer, which is then returned to a cassette 10.
Although cluster tool configurations are generally preferred for processing relatively small substrates, a second method of processing substrates known as an xe2x80x9cinlinexe2x80x9d system is generally preferred for processing larger substrates. These larger substrates, which may be formed on glass, ceramic plates, plastic sheets, or disks, for example, are often used in the manufacture of flat panel type displays in the form of active matrix televisions, computer displays, liquid crystal display (LCD) panels, and other displays. A typical glass substrate supporting a common flat panel type display may have dimensions of approximately 680 mm by 880 mm. For other display applications, the size of the substrate may be substantially larger, as required to support the particular size of the display.
FIG. 2 is a schematic side view of a typical modular inline system 40. This type of processing system generally includes a serial or inline arrangement of processing chambers 42, 44 disposed between a load chamber 46 and an unload chamber 48. An elevator 50 is positioned at an entry to load chamber 46 and another elevator 52 is positioned at an exit from unload chamber 48. Processing chambers 42, 44 may include deposition chambers, such as chemical vapor deposition (CVD) chambers, physical vapor deposition (PVD) chambers, etch chambers, and/or other deposition and processing chambers. A carrier return line 58 is positioned above processing chambers 42, 44 and coupled to the elevators 50, 52. Processing chambers 42, 44 are typically held under vacuum or low pressure and are separated by one or more isolation valves 60, 62, 64, 66, and 68, as shown in FIG. 3. Typically, multiple substrates 54, 56, 70, 72 are supported by a carrier 74, as shown in FIGS. 4 and 5. Isolation valves 60, 62, 64, 66, and 68 are generally configured to seal the respective chambers from each other in a closed position and allow substrates 54, 56 to be transferred through the valves to an adjacent station in an open position.
Carrier 74, shown in FIG. 2, is placed adjacent elevator 50, where substrates 54, 56, 70, 72 are manually loaded onto carrier 74 at receiving station 51. A door to the elevator 50 (not shown) opens and allows carrier 74 to be placed within the elevator on a track (not shown). The temperature and pressure inside elevator 50 is typically at ambient conditions. Isolation valve 60 opens and allows carrier 74 to be moved on the track into load chamber 46. Load chamber 46 is sealed and pumped down to a vacuum typically in a range of about 10 mTorr to about 50 mTorr for CVD processing and about 1 mTorr to about 5 mTorr for PVD processing. Another isolation valve 62 is opened and carrier 74 is moved into a processing chamber 42, where the substrates may be heated to a temperature suitable for processing. Another isolation valve 64 is opened and carrier 74 is moved along the track into processing chamber 44. If processing chamber 44 is a sputtering process chamber, the chamber could include a plurality of targets 76, 78 that sputter material from the surface of the targets facing the substrates onto substrates 54, 56, 70, 72 as the substrates move along the track adjacent each target. Each sputtering target is bombarded on the side facing the substrate with ionized gas atoms (ions) created between an anode (typically the target) and a cathode (typically the grounded chamber wall) and atoms of the target are dislodged and directed toward the substrates for deposition on the substrates. Each target preferably has a magnet (not shown) disposed on the back side of the target away from the substrates to enhance the sputtering rate by generating magnetic field lines generally parallel to the face of the target, around which electrons are trapped in spinning orbits to increase the likelihood of a collision with, and ionization of, a gas atom for sputtering. Substrates 54, 56, 70, 72 are then moved to an unloading chamber 48 through isolation valve 66. Isolation valve 66 closes, thereby sealing processing chamber 44 from unload chamber 48. Isolation valve 68 opens and allows carrier 74 to be removed from unloading chamber 48 and substrates 54, 56, 70, and 72 are typically unloaded manually from carrier 74. The substrates can also be detained in the unloading chamber to allow time for the substrates to cool. After the substrates have been unloaded, carrier 74 enters elevator 52, whereupon elevator 52 lifts carrier 74 to carrier return line 58. A track system (not shown) in carrier return line 58 returns the carrier to elevator 50, which lowers the carrier into position at receiving station 51 on the other end of the processing system to receive a next batch of substrates to be processed.
While the inline system 40 is currently used for substrate transportation and production, this type of inline system has several disadvantages. In particular, carrier 74 is subject to thermal cycling as a result of the movement of carrier from the processing environment (under vacuum) to an ambient environment in elevators 50, 52, and then back into the processing environment. As a result of thermal cycling, deposition material is likely to peel off or be otherwise dislodged from carrier 74 and cause unwanted particle contamination on the substrates. Additionally, the use of the exposed track system, both within the processing chambers and in the ambient areas of the system, is subject to generating contaminants. Further, the use of the elevators and a track system adds a level of complexity to the system, which results in additional maintenance of the various moving components in order to avoid breakdowns. Further still, as a result of carrier 74 cycling through vacuum environments and ambient atmospheric pressure, carrier 74 is prone to absorb gases from the surrounding conditions in the ambient environment, which inevitably increases the chamber pressure and causes contamination of deposited film layers when the gasses absorbed in the ambient atmospheric environment outgass from carrier 74 into the vacuum environment. In addition to the thermal cycling of carrier 74, the mean temperature of carrier 74 typically rises as multiple sets of substrates are processed therewith at temperatures above ambient conditions in the processing environment. Since most processes in processing chambers are temperature sensitive, this rise in carrier temperature increases the probability that the resulting deposition process will produce inconsistent films, as heat transfer from carrier 74 may affect the substrate and/or process properties. This unmonitored variance in the substrate temperature may result in films created at the beginning of a production cycle varying from films created at the end of the production cycle. Yet another challenge with a typical inline system is cross contamination between processes in adjacent processing chambers, especially those chambers using a reactive deposition process. Reactive processing generally depends on two or more constituents in proper proportions, and therefore, an influx of constituents from adjacent processing regions may cause the reactive processing to be unstable and/or adversely affect the deposition characteristics on one or both processing regions.
Therefore, in view of the plain disadvantages resulting from present inline processing systems, there remains a need for an improved inline system and method for processing substrates. In particular, there is a need for an improved inline system capable of processing relatively large and flat substrates though multiple inline deposition regions. Furthermore, there is a need for an inline processing system capable of processing substrates of sufficient size to support large flat panel displays.
The present invention generally provides a system for processing substrates having a carrier disposed primarily in at least one processing chamber and at least one shuttle for transferring substrates between the processing chamber and a load lock chamber. A plurality of processing chambers, load lock chambers, and other chambers can be joined to create a substantially inline series of modular chambers through which substrates are processed. The carrier of the present invention is generally only exposed to the processing environment, i.e., the carrier generally does not shuttle into a non-processing chamber. Therefore, during continuous sequential processing of substrates, thermal cycling of the carrier will be reduced and possibly eliminated. The carrier is reversibly moved within the processing chamber along a concealed track. Multiple processing zones separated by partitions allow a plurality of processing regimes to occur within the same processing chamber without interference. Further, the operating temperature of the carrier in the present invention is temperature controlled by one or more temperature-controlled plates designed to radiate and/or absorb heat to/from the carrier in order to achieve a predefined carrier temperature.
In one embodiment, the present invention provides an apparatus for processing substrates, wherein the apparatus includes at least one substrate carrier for transporting a substrate within a processing environment, at least one temperature controlled plate selectively in communication with the at least one carrier, and at least one deposition device positioned proximate the at least one substrate carrier. The at least one deposition device generally being configured to deposit a selected film upon the substrate.
In another embodiment, the present invention provides a method for processing substrates, wherein the method includes the steps of transporting a substrate into a processing environment on at least one substrate carrier, and transferring the substrate to a substrate support plate inside the processing environment. Further steps of transporting the substrate support plate having the substrate thereon through at least one processing zone in the processing environment and transferring the substrate from the substrate support plate to the at least one substrate carrier for removal from the processing environment are also provided.
In another embodiment, the present invention provides a method for producing a poly silicon film, wherein the method includes the steps of loading a substrate into a processing environment, exposing the substrate to at least one deposition source in the processing environment, exposing the substrate to an annealing device in the processing environment, and removing the substrate from the processing environment. Further, the method includes the step of maintaining and/or controlling the temperature of a substrate through the use of one or more temperature controlled plates.